1. Field of the Invention
The present invention relates to an optical movement sensing system used in an optical pointing device, and more particularly, to an optical movement sensing system which can be miniaturized and ensures a wide angle of view.
2. Description of the Related Art
FIG. 1 is a schematic view illustrating an operational principle of a general optical pointing device.
As shown in FIG. 1, the optical pointing device includes a light source 11, a lens 13, and an image sensor 14. The light source 11 generally employs a light emitting diode (LED) and emits light. The lens 13 collects light reflected from an object 12 by the light emitted from the light source 11. The optical sensor 14 senses an image of the light collected by the lens 13 and detects movement of the object 12. The optical sensor 14 may adopt an image sensor.
The object 12 is configured as a ground or a pad corresponding to the ground in case of a general optical mouse. With a user moving the optical mouse, a relative movement of the object (ground) is detected by the optical sensor 14 to perform pointing (positioning).
Recently, attempts have been made to apply this optical pointing device to a mobile device such as a mobile telecommunication terminal.
As described above, the optical pointing device for use in the mobile telecommunication terminal employs a finger surface as an object and performs pointing by sensing movement of a finger or fingerprint through the optical sensor 14.
However, the conventional optical pointing device, when employed in practice, prevents big movement of the finger, thereby causing great discomfort to users accustomed to the general optical mouse.
As described above, to apply the optical pointing device to the mobile device such as the mobile telecommunication terminal, an optical sensing system should be small and should ensure peripheral light amount. Also, the optical system should ensure a wide angel of view so as to perceive big movement of the fingers.
Therefore, an optical movement sensing system has been in demand to overcome these limitations.